Study Of Computer-Aided Diagnosis And Tuning Of Microwave Filters

This thesis focuses on the computer-aided diagnosis and tuning method for cascaded coupled and cross-coupled resonator cavity filters.First of all, the general coupling matrix synthesis methods for generalized Chebyshev filtering functiongs and the designing steps of cavity filters are analyzed. Then, base on the equivalent circuit model for cascaded coupled resonator filter, the method for measuring or computing the phase of the reflection coefficient of short-circuit terminated networks and synthesizeing all the inter-resonator couplings and resonant frequencies of the filters to be tuned is studied intensively. The phase loading effect is removed and the tuning steps are analyzed. The method based on the partial fraction expansions of admittance matrix is used to synthesize coupling matrix of the filters under tuning. The method for removing the phase loading effect is discribed. Finally, combined the two methods, the tuning of several cascaded and cross coupled bandpass cavity filters is demonstrated by HFSS.